Immediately invalidates all existing items.
Memcached does not support flush() per default. If you require flush() support, set $config[“statsKey”].
All modified keys are stored in “statsKey”. Note: statsKey has a negative performance impact.

<?php$cache=new\Phalcon\Cache\Backend\Libmemcached($frontCache,["statsKey"=>"_PHCM",]);$cache->save("my-data",[1,2,3,4,5]);// 'my-data' and all other used keys are deleted$cache->flush();